1. Field of Invention
This invention relates to a pre-machined, engineered, perimeter rim board that incorporates joist recessed receptacles that may be manufactured to be universally compatible with all existing and preferably all future I-joists and other manufactured joist products. This invention may be one component in a series of products that comprise installation and structural enhancements for wood frame building construction projects.
2. Related Art
Numerous companies manufacture I-joists, dimensional lumber and other wood products which are used as floor joists and roof rafters in frame building construction. According to I-joist manufacturers, the advantages of I-joists over solid lumber and other wood products include: a) lightweight for ease of handling, b) product uniformity and consistency, c) availability of long lengths, d) high structural integrity, and e) the conservation of old growth forests through use of composite wood fiber materials.
I-joists are comprised of top and bottom flanges made of solid wood, laminated veneer lumber (LVL) and/or oriented strand lumber (OSL), the top and bottom flanges being at the top and bottom edges of a thin center web made of plywood, oriented strand board (OSB) or other structurally approved materials. While these products are well engineered for uniformly distributed top load conditions, the thin web creates unique challenges for solid, stable and secure attachments to conventional rim boards.
Presently, conventional flat-surfaced rim boards, which have rectangular cross section end profiles and which are not machined, are available in the same depths as I-joists. The purpose of these rim boards is to provide stability and additional load capabilities to the ends of I-Joists. Builders have to specifically measure each joist or rafter location before placement and attachment to conventional rim boards.
Most manufactures of I-joists publish details for securing the rim board to joist ends by using a single 8 d box or 10 d box nail into each end of both the top and bottom flanges of the I-joist. This does not favorably compare with the strength of three or four 16 d box nails used to secure rim boards onto the ends of conventional solid framing lumber. Additionally, a minimal attachment of a conventional non-machined rim board to I-joists may not, in many cases, meet today's strict lateral load (wind and seismic) code requirements. Many architects, engineers and designers are faced with specifying special on-site supplemental blocking inside the rim board, which is time consuming and tedious, and which requires additional materials and more labor and creates potential challenges for cutting squarely and to exact proper length.
Practically speaking, many of these on-site structural details, such as the on-site supplemental blocking, are improperly followed or ignored altogether in the field. Therefore, a need exists for a pre-machined rim board product that is easy to install and enhances the structural stability of this important connection while saving time and expense. Further, a need exists for a product that facilitates framing accuracy for all joist and rafter installations while protecting the integrity of I-joists in particular. The present invention meets these needs.